Question: Simplify the following expression: $y = \dfrac{k^2 - 11k + 18}{k - 9} $
Explanation: First factor the polynomial in the numerator. $ k^2 - 11k + 18 = (k - 9)(k - 2) $ So we can rewrite the expression as: $y = \dfrac{(k - 9)(k - 2)}{k - 9} $ We can divide the numerator and denominator by $(k - 9)$ on condition that $k \neq 9$ Therefore $y = k - 2; k \neq 9$